Oil and Gas Well Primary Separation Device

ABSTRACT

A primary separation apparatus for separating natural gas from high pressure, high velocity production streams comprising a liquid dispersion of water, sand, natural gas, and isolation plug cuttings.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application Ser. No. 61/813,744 filed Apr. 19, 2013, whichis incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to oil and gas well completion and production.

2. Description of the Prior Art

Geologists have known for years that substantial deposits of oil andnatural gas are trapped in deep shale formations. Around the worldtoday, with modern horizontal drilling techniques and hydraulicfracturing, the trapped oil and natural gas in these shale reservoirs isbeing produced, gathered and distributed to customers.

Initially, a vertical hole is drilled in a formation down to a depthbelow the water table, and steel casing is inserted into the boreholeand cemented in place, thus providing an impermeable barrier between thewater table and borehole. Vertical drilling continues to a depth calledthe “kick-off” point, where the wellbore begins curving to becomehorizontal. One advantage of horizontal drilling is that it is possibleto drill several wells from only one drilling pad, minimizing the impactto the surface environment. When the targeted distance is reached, thedrill pipe is removed from the borehole, and additional steel casing isinserted through the full length of the wellbore and cemented in place.

The drilling rig is then removed and preparations for well completionare then undertaken. The first step is to create a connection betweenthe final casing and the reservoir rock. To do so, a device known as aperforating gun, equipped with shaped explosive charges, is lowered intothe wellbore down to the layer containing oil and/or natural gas. Theperforating gun is then fired, which creates holes through the casing,cement, and into the target reservoir rock. Next, a mixture of water,sand and other chemicals is pumped into the deep underground reservoirformations, which creates fractures in the reservoir rock. A proppingagent, usually sand carried by the high viscosity fluid, is pumped intothe fractures to keep them from closing when the pumping pressure isreleased. This initial stimulation segment is then isolated with aspecially designed plug inserted into the steel casing to seal off theperforated (and thus the fractured reservoir) and prevent productionfrom the isolated section. The perforating gun is then moved to the nextstage of the wellbore to perform the same process, which is thenhydraulically fractured in the same manner. This process is repeatedalong the entire horizontal section of the well, which may extendseveral miles.

Once the stimulation is complete, the isolation plugs are drilled outand production begins. Initially water, and then natural gas or oilflows into the horizontal casing and up the wellbore. In the course ofinitial production of the well, approximately 15 to 50% of thefracturing fluid may be recovered, a process known as “flowback.” Thepurpose of the flowback is to safely recover these substances from thewell and transition the marketable hydrocarbons of the well stream to asales pipeline or storage tank. The fracturing fluid is then eitherrecycled to be used on other fracturing operations or safely disposed ofaccording to government regulations.

The fracturing process described above requires equipment to handle andseparate drilled isolation plug cuttings along with large volumes ofsand, fracturing fluids, and oil and natural gas. The drilled isolationplug cuttings and sand need to be separated to keep from plugging otherfluid clean up and separation equipment, which may cause a loss ofcirculation detrimental to downhole tools. Accordingly, a device isneeded to efficiently separate drilled isolation plug cuttings, sand,fracturing fluids and oil and natural gas during a flowback process ofproduction of fluids from the wellbore.

IDENTIFICATION OF THE OBJECTS OF THE INVENTION

An object of the invention is to accomplish one or more of thefollowing:

Provide an apparatus for primary separation in fracking operations thatcombines isolation plug cutting separation, sand separation, and gasseparation in a single separation assembly.

SUMMARY OF THE INVENTION

In one aspect, embodiments disclosed herein relate to an apparatus forseparating natural gas from high pressure, high velocity productionstreams comprising a liquid dispersion of water, sand, natural gas, andisolation plug cuttings. The apparatus includes a housing having a firstend and a second end, and an interior cavity extending therebetween, andan inlet port disposed at said first end of said housing. A flow sleeveis disposed within said interior cavity of said housing and extendingfrom said first end to said second end of said housing, and a firstscreen is disposed within said flow sleeve and in fluid communicationwith said inlet port. An annulus is formed between an outer diameter ofsaid first screen and an inner diameter of said flow sleeve. A baffle isdisposed within said interior cavity at said second end of said housing,and said baffle is arranged and designed to enhance separation of saidproduction stream into its constituents, a liquid drain in a lowerportion of said housing, a second screen coupled to an upper portion ofsaid housing, and a gas outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the accompanying drawings wherein,

FIG. 1A illustrates a cross-section view of a primary separator inaccordance with one or more embodiments of the present disclosure;

FIG. 1B illustrates an enlarged cross-section view of a second end ofthe primary separator of FIG. 1A; and

FIG. 2 the primary separator of FIG. 1A on location.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The aspects, features, and advantages of the invention mentioned aboveare described in more detail by reference to the drawings, wherein likereference numerals represent like elements. FIG. 1 illustrates across-section view of a primary separator 100 in accordance with one ormore embodiments of the present disclosure.

Main Housing

The primary separator 100 includes a generally cylindrical main housing102 having a first flange 104 on a first end and a second flange 106 ona second end. The main housing 102 complies with all PSL-3 NACE H₂Sspecifications. The main housing 102 is rated for pressures of at least5,000 psi, 10,000 psi, 15,000 psi, and up to 20,000 psi. A generallycylindrical interior cavity 108 or bore is formed within the mainhousing 102. An inlet port 110 may be coupled to the main housing 102 byway of a first adaptor 112 that is fastened to the first flange 104 withone or more threaded fasteners 114. One or more valves 116, 118 may bedisposed between the inlet port 110 and adaptor 112. Valves 116, 118 maybe gate valves, either manually or hydraulically operated, or othervalves known to one of ordinary skill in the art for opening or closinginlet port 110 to allow production fluid to enter the primary separator100. Alternatively, inlet port 110 may be fastened directly to the firstflange 104 of the main housing 102. A pressure gauge 137 may be coupledto the inlet port 110 and arranged and designed to monitor pressureentering the inlet port 110.

A second adaptor 120 may be fastened to the second flange 106 of themain housing 102 by way of one or more fasteners (not shown). Further,an end cap 122 may have an internal thread that engages an externalthread of the second adaptor 120 and is threaded thereon. The end cap122 is preferably removable from the second adaptor 120. Alternatively,the end cap 122 may be attached directly to the second flange 106 of themain housing 102 by way of one or more threaded fasteners.

The main housing 102 further includes a top flange 124. A top flowadaptor 126 is disposed within the top flange 124 and secured therein byway of one or more threaded fasteners 128. The top flow adaptor 126 mayhave a flow channel therein that decreases in diameter from a bottomsurface of the flow adaptor to the top surface. One or more sealingmembers 130 may be installed between the top flow adaptor 126 and thetop flange 124.

The main housing 102 also includes a bottom flange 130. A bottom flowadaptor 132 or flow block is disposed within the bottom flange 130 andsecured therein by way of one or more threaded fasteners 134. The bottomflow adaptor 132 may have a flow channel therein that decreases indiameter from a top surface of the flow adaptor to a bottom surface. Oneor more sealing members 136 may be installed between the bottom flowadaptor 132 and the bottom flange 130. The bottom flow adaptor 132includes an outlet port 138 or drain through which fluid or sediment mayflow out of the main housing 102.

Finally, a pressure gauge 139 may be coupled to the main housing 102 andarranged and designed to monitor pressure within the interior cavity 108of the main housing 102.

Plug Cuttings Screen Assembly

A screen assembly 140 is disposed within the interior cavity 108 of themain housing 102. The screen assembly 140 includes a flow sleeve 142that extends within the interior cavity 108 of the main housing from afirst end to a second end of the main housing 102. A first end of theflow sleeve 142 is threaded within the first flange 104 of the mainhousing 102 and abuts the first adaptor 112 coupled to the first flange104. A second end of the flow sleeve 142 is threaded within the secondflange 106 and abuts the second adaptor 120. The flow sleeve 142 ispreferably a hollow cylindrical tube having an inner diameter of atleast about 3 inches, 4 inches, or 5 inches, up to about 6 inches, 7inches or 8 inches. The flow sleeve 142 has one or more ports 145 a and145 b located proximate the second end of the flow sleeve 142, whichallow gas and fluid to exit the flow sleeve 142 and enter the interiorcavity 108 of the main housing 102. As best illustrated in FIG. 1B,upper port 145 a may have a diameter of at least about ½ inch, ¾ inch,or 1 inch, up to about 1½ inches, 1¾ inches, or 2 inches. Lower port 145b may have a diameter of at least about 1½ inches, 2 inches, or 2½inches, up to about 3 inches or 4 inches.

A screen 144 is disposed within the flow sleeve 142. The screen 144 isconcentrically oriented within the flow sleeve 142 and extends axiallywithin the flow sleeve 142. A first end of the screen 144 has a collar146 attached thereto (e.g., welded). The collar 146 is adapted to fitwithin a seat or pocket 113 of the first adaptor 112 coupled to thefirst flange 104. A second end of the screen 144 has a collar 148attached thereto (e.g., threaded as shown, or welded). The collar 148 isadapted to fit within the second adaptor 120 and extend through anaperture in the end cap 122. The collar 148 has a flange 149, whichabuts between surfaces of the second adaptor 120 and the end cap 122.When the end cap 122 is installed over the collar 148 and threaded ontothe second adaptor 120, the interface between the flange 149 of thecollar 148 between the second adaptor 120 and the end cap 122 preventsmovement of the screen 142 in an axial direction. Removal of the end cap122 allows the screen 142 to be removed, either for replacement orcleaning.

The screen 144 is preferably a stainless steel hollow cylindrical tubethat has a plurality of perforations to allow a fluid to enter thehollow tube and radially exit the screen through the plurality ofperforations. The screen may have an inner diameter of at least about 1inch, 2 inches, or 3 inches, up to about 4 inches, 5 inches, or 6inches. An annulus 143 is formed between an outer diameter of the screen144 and an inner diameter of the flow sleeve 142. Perforations in thescreen 144 may have a diameter of at least about ⅛ inch, ¼ inch, or ⅜inch up to about ½ inch, 9/16 inch, ⅝ inch, ¾ inch, or 1 inch. In otherembodiments, perforations in the screen 144 may have a diameter of up toabout 1½ inches, 2 inch, or 3 inches.

Further, a baffle 150 is located within the interior cavity 108 at asecond end of the main housing 102 proximate the second flange 106. Thebaffle 150 is preferably a plate welded or otherwise attached to anouter diameter of the flow sleeve 142. The plate may be at least about 1inch in thickness, and up to about 3 inches in thickness. The baffle 150is extends radially outward from the outer diameter of the flow sleeve142 towards an inner wall of the housing 102. The baffle 150 is sized tohave an outer diameter that is less than an inner diameter of thehousing 102 so that an upper passageway 152 and a lower passageway 154(e.g., gaps) are formed there between. The baffle 150 is arranged anddesigned to distribute fluid flow exiting from ports 145 a and 145 binto a larger pattern within the interior cavity 108 of the housing 102and to further separate gas from fluids.

Gas Separator Assembly

A gas separator assembly 160 is coupled to the top flow adaptor 126 byway of one or more threaded fasteners 162. The gas separator assembly160 includes a riser spool or lower body 164 having a central bore therethrough. An outlet body 166 having one or more outlets 168, both radialand longitudinal, may be coupled to the lower body 164 by way one ormore threaded fasteners 169. In certain embodiments, a blind flange 170may be disposed over at least one of the radial outlets therebydirecting fluid out remaining radial outlets 168. A tree cap 170 may befastened to the outlet body 166 by way of one or more threaded fasteners171. Finally, a threaded cap 174 having internal threads may be threadedonto external threads of the tree cap 172. Alternatively, the gasseparator assembly 160 may comprise or be formed as a single integralhousing attached to the top flow adaptor 126 of the main housing 102 andcomprising the individual components previously described in a singleintegral component.

The gas separator assembly 160 further includes a screen 178 disposedtherein. The screen 178 is preferably a stainless steel hollowcylindrical tube that has a plurality of perforations to allow a fluidto enter the hollow tube and radially exit the screen through theplurality of perforations. The screen 178 may have an outer diameter ofat least about 1 inch, 2 inches, or 3 inches, up to about 4 inches, 5inches or 6 inches. Perforations in the screen 178 may have a diameterof at least about 20 microns, 30 microns, or 40 microns, up to about 50microns, 60 microns, 70 microns or 80 microns. In other embodiments, theperforations may have a diameter up to about ⅛ inch, ¼ inch, ½ inch or 1inch.

A lower end of the screen 178 may be installed in a seat 180 attachedwithin a lower end of the lower body 164. For example, the seat 180 maybe welded within the lower body 164. An upper end of the screen 178 maycomprise a collar 182, attached to the screen 178, either welded orthreaded. The collar 182 is adapted to fit within the tree cap 172 andextend through an aperture in the threaded cap 174. Removal of thethreaded cap 174 allows the screen 178 to be removed, either forreplacement or cleaning. In certain embodiments, the collar 182 may havea needle valve 176 or the like installed therein for pressure adjustmentwithin the gas separator assembly 160.

Methods of Use

FIG. 2 is a simplified schematic showing the primary separator 100installed in a flowback system 5. A fracturing tree 10 (“frac tree”) isdisposed on a producing well from which a production fluid containing amixture of fracking fluids, drilled isolation plug cuttings, oil andnatural gas, water, and sand or other sediment flows. The productionfluid flows from the frac tree 10 through a fluid line 12 and enters theprimary separator 100. The primary separator 100 separates drilled plugcuttings, natural gas, and fluid and sand in a single integral primaryseparator 100.

In reference to FIGS. 1A and 1B, the production stream enters theprimary separator 100 through the inlet port 110 and flows into screen144. As the production fluid flows through the screen 144, fluids,including fracking fluids, oil and natural gas, and water, and smallersolid matter such as sand particles and similar sediment pass radiallyoutward through the plurality of perforations in the screen 144 into theannulus 143 formed between the screen 144 and flow sleeve 142. Largersolids, particularly, drilled isolation plug cuttings are caught withinthe screen 144 and prevented from passing through the plurality ofperforations. Fluid and smaller solids continue to flow either throughscreen 144 or within annulus 143 (e.g., in a swirling motion as shown inFIG. 1B) until they reach a second end of the screen assembly 140 andports 145 a and 145 b. Some separation of gas particles from the fluidsand smaller solids occurs in the annulus 143 through cyclonic separation(i.e., swirling motion), which will be understood by one of ordinaryskill in the art.

Once the swirling flow reaches a second end of the flow sleeve 142 andannulus 143, fluids and smaller solid matter within the annulus 143 flowdownward through lower port 145 b, while gas particles flow upwardthrough upper port 145 a. Fluids and smaller solid matter as well as gasparticles then encounter the flow baffle 150, which is arranged anddesigned to cause flow distribution and encourage further separation ofgas from well fluids such as oil, water, and/or fracking fluids, andsand or sediment.

Fluid and sand separation from the gas within the primary separationdevice is dependent on gravity and retention time. In certainembodiments, fluid may circulate through the primary separation deviceat a rate of between about two and three barrels per minute. In otherembodiments, fluid may circulate through the primary separation deviceat a rate of between about two and twenty barrels per minute. Onceseparated from the gas, fluids and solid matter flow downward throughthe lower port 154 of the flow baffle 150 to the liquid drain 138 at thebottom of the main housing 102. Once separated from fluids and solidmatter at the baffle, the gas flows through the upper port 152 of theflow baffle 150 to an upper portion of the main housing 102. The gasenters the gas separator assembly 160, where the gas flows into thescreen 178. As gas flows radially outward through the plurality ofperforations in the screen 178, sand and other small sediment isfiltered and remains in the screen 178. Filtered gas then exits the gasseparator assembly 160 by way of outlet 168.

As shown in FIG. 2, filtered gas exiting outlet 168 flows through a gasline 14, through a flow regulator 15 (e.g., a choke valve), and may befurther processed in a three-phase separator 16. Liquid and solid matterexiting liquid drain 138 may flow through a fluid-sand clean-up line 18to one or more deposit tanks (not shown).

Advantageously, the primary separator provides separation of drilledisolation plug cuttings, gas, and well fluids and sand in a singleassembly before said constituents reach other fluid handling equipmentnot suitable for handling such a mixture. What's more, the combinedseparation capabilities of drilled isolation plug cuttings, gas, andwell fluids and sand in a single assembly greatly reduces the footprintfor such equipment, where floor space is often at a premium.Additionally, the removable screens allow screens to be easily removedand cleaned or replaced, which increases the efficiency of theseparation process. Furthermore, once the isolation plugs are drilledand the well is being cleaned up, the primary separator described hereinmay perform as a sand trap, which may include one or more sand filtersto trap trace sand.

In other words, screen 144 may be replaced in about ten minutes or lesswith a sand filter having from 20 to 80 micron perforations.

What is claimed is:
 1. An apparatus (100) for separating natural gasfrom high pressure, high velocity production streams comprising a liquiddispersion of water, sand, natural gas, and isolation plug cuttings,said apparatus comprising: a housing (102) having a first end and asecond end, and an interior cavity (108) extending therebetween; aninlet port (110) disposed at said first end of said housing; a flowsleeve (142) disposed within said interior cavity of said housing andextending from said first end to said second end of said housing; afirst screen (144) disposed within said flow sleeve and in fluidcommunication with said inlet port, wherein an annulus (143) is formedbetween an outer diameter of said first screen and an inner diameter ofsaid flow sleeve; a baffle (150) within said interior cavity at saidsecond end of said housing, wherein said baffle is arranged and designedto enhance separation of said production stream into its constituents; aliquid drain (138) in a lower portion of said housing; a second screen(178) coupled to an upper portion of said housing; and a gas outlet(168).
 2. The apparatus of claim 1, further comprising a plurality ofperforations in said first screen (144) having a diameter of at leastabout ⅛ inch up to about 3 inches.
 3. The apparatus of claim 1, saidflow sleeve further comprising one or more ports (145 a, 145 b) locatedproximate a second end of said flow sleeve.
 4. The apparatus of claim 1,further comprising a plurality of perforations in said second screen(178) having a diameter of at least about 20 microns up to about 1 inch.5. The apparatus of claim 1, wherein said baffle (150) is sized to havean outer diameter that is less than an inner diameter of said housing(102) thereby forming an upper passageway (152) and a lower passageway(154) there between.
 6. The apparatus of claim 1, further comprising apressure gauge (137) coupled to said inlet port (110) and arranged anddesigned to monitor pressure entering said inlet port.
 7. The apparatusof claim 1, further comprising a pressure gauge (139) coupled to saidmain housing (102) and arranged and designed to monitor pressure withinsaid interior cavity (108) of said main housing.
 8. The apparatus ofclaim 1, wherein said first and second screens are removable from saidhousing for replacement or cleaning.
 9. A flowback system comprising: afracturing tree (10) disposed on a producing well from which a highpressure, high velocity production stream comprising a liquid dispersionof water, sand, natural gas, and drilled plug cuttings flows; a primaryseparator (100) configured for receiving said production stream througha fluid line (12) from said fracturing tree, the primary separatorcomprising: an isolation plug cutting separator comprising a firstscreen (144) having a plurality of perforations and extending axiallywithin a flow sleeve (142), wherein said perforations are configuredhaving a diameter such that drilled plug cuttings remain within saidfirst screen; a gas separator comprising a second screen (178) having aplurality of perforations configured having a diameter such that gasparticles flow outwardly through the perforations and sand and othersmall sediment remains within said second screen; a three-phaseseparator (16) configured for receiving gas particles separated in saidgas separator and exiting said primary separator through a gas line(14); and a fluid-sand clean-up line (18) configured for removingseparated liquid and solid matter exiting said primary separator. 10.The flowback system of claim 9, wherein said plurality of perforationsin said first screen (144) are configured having a diameter of at leastabout ⅛ inch up to about 3 inches.
 11. The flowback system of claim 9,wherein said plurality of perforations in said second screen (178) areconfigured having a diameter of at least about 20 microns up to about 1inch.
 12. The flowback system of claim 9, the primary separator furthercomprising a liquid drain (138) through which liquid and solid mattermay flow out of said primary separator into said fluid-sand clean-upline (18).
 13. The flowback system of claim 9, the primary separatorfurther comprising a gas outlet (168) through which gas particles mayflow out of said primary separator into said gas line (14).
 14. A methodof processing a production fluid containing a mixture of frackingfluids, drilled isolation plug cuttings, oil and natural gas, water, andsand or other sediment and small solid matter using a single separationdevice, the method comprising: flowing said production fluid into saidseparation device (100) through an inlet port (110) and through a firstscreen (144), thereby trapping drilled isolation plug cuttings withinsaid first screen and filtering fluids and smaller solid matter radiallyoutward through perforations of said first screen; impinging filteredfluids and smaller solid matter on a flow baffle (150), thereby furtherseparating gas particles from said filtered fluids; flowing separatedgas particles through a second screen (178), thereby trapping remainingsand and other small sediment within said second screen, wherein saidseparated gas particles then exit said separation device; and evacuatingremaining separated fluids and solid matter through a liquid drain (138)at a bottom portion of said separation device.
 15. The method of claim14, further comprising flowing said production fluid through saidseparation device at a rate of between about two and twenty barrels perminute, thereby optimizing separation mechanisms dependent on gravityand retention time.
 16. The method of claim 14, further comprisingprocessing said separated gas particles, after exiting said separationdevice, in a three-phase separator (16).
 17. The method of claim 14,further comprising transferring said separated fluids and solid matter,after exiting said separation device, through a fluid-sand clean-up line(18).